The invention relates to a fully automatic, closed and sterile system for performing whole blood separation and component removal in a centrifugal field and for performing addition of storage solution.
The currently used manual methods used for separating components from a unit of whole blood are labor-intensive, lengthy, and costly. The current primary method for separating whole blood into components is to centrifuge the blood bag in order to separate plasma from red cells. A xe2x80x9csoftxe2x80x9d spin at moderate centrifuge speeds results in a platelet-rich plasma. The bag is removed from the centrifuge and a bag flat-plate press is used to manually expel separated plasma from the blood bag into another bag. This second bag may then be spun in the centrifuge to separate platelets from plasma. A bag press is used to express platelet-poor plasma into a third bag, retaining platelet-rich plasma in the second bag.
An alternative procedure uses a xe2x80x9chardxe2x80x9d spin or higher centrifuge speed of the blood bag to separate blood into red cells, platelet-poor plasma, and a buffy coat between the red cells and plasma that contains most of the white cells and platelets. As with the xe2x80x9csoftxe2x80x9d spin method, however, the plasma is manually expelled into another bag using a bag flat-plate press. The bag press is used again to expel the buffy coat into a third bag, and a separate process is used to separate the platelets from the buffy coat. xe2x80x9cHardxe2x80x9d and xe2x80x9csoftxe2x80x9d spins are terms well-understood in the artxe2x80x94although the revolutions per minute associated with hard or soft spins varies with the size of the centrifuge. In many centrifuges used in blood separation procedures, a xe2x80x9csoftxe2x80x9d spin is achieved at approximately 3000 rpm while a xe2x80x9chardxe2x80x9d spin is achieved at between 5000-6000 rpm.
Both of the above procedures can also result in red cell contamination of plasma and platelets. The procedures can also result in higher than desirable white cell and platelet concentrations in the red cells and higher than desirable white cell concentration in the platelets.
It is generally desirable to wash concentrated red cells, such as those produced by the Blood Processing System, U.S. patent application Ser. No. 09/419,216, which is incorporated by reference herein, in a wash solution that increases the shelf life of the cells. The wash solution is added to the red cells, mixed, and centrifuged to separate the excess solution from the cells. The excess wash solution is then removed. However, manual methods for washing red cells within a closed system use a sterile connection (sterile docking) to introduce and remove wash solution between centrifugal cycles, which is labor-intensive and costly. As a result, the addition of a washing step prior to storage cannot be justified economically, even if the result was a doubling of shelf life.
An alternative is to mix the concentrated red cells with a long-term storage solution without washing. One current solution uses hundred milliliters of additive to a unit of concentrated red cells and can provide up to six weeks of refrigerated storage. In automatic processes the long-term storage solution may be utilized without sterile docking procedures, reducing the cost of the procedure to an acceptable level.
It is therefore an object of the invention to provide a completely automated apparatus and method that separates whole blood into blood components with a high degree of reproducible quality and consistency, reducing or eliminating component cross-contamination. It is a further object of the invention to reduce user set-up time, processing time, and removal time with safe operation. It is a further object of the invention to utilize standard centrifuges modifications and allow the user to select a variety of automatic processes and options without hardware modifications, since blood banks have limited space and require equipment to be heavily used and versatile. It is a further object of the invention to provide disposables (i.e., bag sets) for use in the process that are equivalent in cost or less expensive than those used in current procedures.
The current invention embodies a device and methods for removal of components of blood within a centrifuge that is used for separation of those components. Components may be removed to satellite bags during the centrifugation using the force created by the centrifugal field either as a result of pressure differentials created directly by the centrifugal field or by means of a weighted expresser pushed against the bag by the force. Specially designed tapered, conical bags allow a very sharp separation between components to be maintained and prevent, or significantly reduce, remixing of components during the removal process. Detectors, such as optical detectors, arc used to distinguish between the componentsxe2x80x94red cells, platelets or buffy coat, and plasmaxe2x80x94and provide the input that allows the generation of control signals that open and close tubing pinch valves that direct the component flow to the appropriate component bag.